Merge tag 'bcachefs-2024-05-07.2' of https://evilpiepirate.org/git/bcachefs

Pull bcachefs fixes from Kent Overstreet:

 - Various syzbot fixes; mainly small gaps in validation

 - Fix an integer overflow in fiemap() which was preventing filefrag
   from returning the full list of extents

 - Fix a refcounting bug on the device refcount, turned up by new
   assertions in the development branch

 - Fix a device removal/readd bug; write_super() was repeatedly dropping
   and retaking bch_dev->io_ref references

* tag 'bcachefs-2024-05-07.2' of https://evilpiepirate.org/git/bcachefs:
  bcachefs: Add missing sched_annotate_sleep() in bch2_journal_flush_seq_async()
  bcachefs: Fix race in bch2_write_super()
  bcachefs: BCH_SB_LAYOUT_SIZE_BITS_MAX
  bcachefs: Add missing skcipher_request_set_callback() call
  bcachefs: Fix snapshot_t() usage in bch2_fs_quota_read_inode()
  bcachefs: Fix shift-by-64 in bformat_needs_redo()
  bcachefs: Guard against unknown k.k->type in __bkey_invalid()
  bcachefs: Add missing validation for superblock section clean
  bcachefs: Fix assert in bch2_alloc_v4_invalid()
  bcachefs: fix overflow in fiemap
  bcachefs: Add a better limit for maximum number of buckets
  bcachefs: Fix lifetime issue in device iterator helpers
  bcachefs: Fix bch2_dev_lookup() refcounting
  bcachefs: Initialize bch_write_op->failed in inline data path
  bcachefs: Fix refcount put in sb_field_resize error path
  bcachefs: Inodes need extra padding for varint_decode_fast()
  bcachefs: Fix early error path in bch2_fs_btree_key_cache_exit()
  bcachefs: bucket_pos_to_bp_noerror()
  bcachefs: don't free error pointers
  bcachefs: Fix a scheduler splat in __bch2_next_write_buffer_flush_journal_buf()

20 files changed, 150 insertions, 71 deletions

diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
index 4ff56fa4d53920..534ba2b02bd652 100644
--- a/fs/bcachefs/alloc_background.c
+++ b/fs/bcachefs/alloc_background.c
@@ -244,10 +244,10 @@ int bch2_alloc_v4_invalid(struct bch_fs *c, struct bkey_s_c k,
 	struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(k);
 	int ret = 0;
 
-	bkey_fsck_err_on(alloc_v4_u64s(a.v) > bkey_val_u64s(k.k), c, err,
+	bkey_fsck_err_on(alloc_v4_u64s_noerror(a.v) > bkey_val_u64s(k.k), c, err,
 			 alloc_v4_val_size_bad,
 			 "bad val size (%u > %zu)",
-			 alloc_v4_u64s(a.v), bkey_val_u64s(k.k));
+			 alloc_v4_u64s_noerror(a.v), bkey_val_u64s(k.k));
 
 	bkey_fsck_err_on(!BCH_ALLOC_V4_BACKPOINTERS_START(a.v) &&
 			 BCH_ALLOC_V4_NR_BACKPOINTERS(a.v), c, err,
diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
index 052b2fac25d693..2790e516383d59 100644
--- a/fs/bcachefs/alloc_background.h
+++ b/fs/bcachefs/alloc_background.h
@@ -126,13 +126,17 @@ static inline struct bpos alloc_freespace_pos(struct bpos pos, struct bch_alloc_
 	return pos;
 }
 
-static inline unsigned alloc_v4_u64s(const struct bch_alloc_v4 *a)
+static inline unsigned alloc_v4_u64s_noerror(const struct bch_alloc_v4 *a)
 {
-	unsigned ret = (BCH_ALLOC_V4_BACKPOINTERS_START(a) ?:
+	return (BCH_ALLOC_V4_BACKPOINTERS_START(a) ?:
 			BCH_ALLOC_V4_U64s_V0) +
 		BCH_ALLOC_V4_NR_BACKPOINTERS(a) *
 		(sizeof(struct bch_backpointer) / sizeof(u64));
+}
 
+static inline unsigned alloc_v4_u64s(const struct bch_alloc_v4 *a)
+{
+	unsigned ret = alloc_v4_u64s_noerror(a);
 	BUG_ON(ret > U8_MAX - BKEY_U64s);
 	return ret;
 }
diff --git a/fs/bcachefs/backpointers.c b/fs/bcachefs/backpointers.c
index a200442010025a..af7a71de1bdfeb 100644
--- a/fs/bcachefs/backpointers.c
+++ b/fs/bcachefs/backpointers.c
@@ -54,7 +54,7 @@ int bch2_backpointer_invalid(struct bch_fs *c, struct bkey_s_c k,
 	int ret = 0;
 
 	bkey_fsck_err_on((bp.v->bucket_offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT) >= ca->mi.bucket_size ||
-			 !bpos_eq(bp.k->p, bucket_pos_to_bp(c, bucket, bp.v->bucket_offset)),
+			 !bpos_eq(bp.k->p, bucket_pos_to_bp_noerror(ca, bucket, bp.v->bucket_offset)),
 			 c, err,
 			 backpointer_bucket_offset_wrong,
 			 "backpointer bucket_offset wrong");
diff --git a/fs/bcachefs/backpointers.h b/fs/bcachefs/backpointers.h
index 85949b9fd880ce..c1b274eadda141 100644
--- a/fs/bcachefs/backpointers.h
+++ b/fs/bcachefs/backpointers.h
@@ -45,6 +45,15 @@ static inline struct bpos bp_pos_to_bucket(const struct bch_fs *c,
 	return POS(bp_pos.inode, sector_to_bucket(ca, bucket_sector));
 }
 
+static inline struct bpos bucket_pos_to_bp_noerror(const struct bch_dev *ca,
+						   struct bpos bucket,
+						   u64 bucket_offset)
+{
+	return POS(bucket.inode,
+		   (bucket_to_sector(ca, bucket.offset) <<
+		    MAX_EXTENT_COMPRESS_RATIO_SHIFT) + bucket_offset);
+}
+
 /*
  * Convert from pos in alloc btree + bucket offset to pos in backpointer btree:
  */
@@ -53,10 +62,7 @@ static inline struct bpos bucket_pos_to_bp(const struct bch_fs *c,
 					   u64 bucket_offset)
 {
 	struct bch_dev *ca = bch_dev_bkey_exists(c, bucket.inode);
-	struct bpos ret = POS(bucket.inode,
-			      (bucket_to_sector(ca, bucket.offset) <<
-			       MAX_EXTENT_COMPRESS_RATIO_SHIFT) + bucket_offset);
-
+	struct bpos ret = bucket_pos_to_bp_noerror(ca, bucket, bucket_offset);
 	EBUG_ON(!bkey_eq(bucket, bp_pos_to_bucket(c, ret)));
 	return ret;
 }
diff --git a/fs/bcachefs/bcachefs_format.h b/fs/bcachefs/bcachefs_format.h
index f7fbfccd2b1e4d..2e8b1a489c2092 100644
--- a/fs/bcachefs/bcachefs_format.h
+++ b/fs/bcachefs/bcachefs_format.h
@@ -591,6 +591,12 @@ struct bch_member {
 	__le64			btree_allocated_bitmap;
 };
 
+/*
+ * This limit comes from the bucket_gens array - it's a single allocation, and
+ * kernel allocation are limited to INT_MAX
+ */
+#define BCH_MEMBER_NBUCKETS_MAX	(INT_MAX - 64)
+
 #define BCH_MEMBER_V1_BYTES	56
 
 LE64_BITMASK(BCH_MEMBER_STATE,		struct bch_member, flags,  0,  4)
@@ -897,6 +903,8 @@ unsigned bcachefs_metadata_required_upgrade_below = bcachefs_metadata_version_re
 #define BCH_SB_SECTOR			8
 #define BCH_SB_MEMBERS_MAX		64 /* XXX kill */
 
+#define BCH_SB_LAYOUT_SIZE_BITS_MAX	16 /* 32 MB */
+
 struct bch_sb_layout {
 	__uuid_t		magic;	/* bcachefs superblock UUID */
 	__u8			layout_type;
diff --git a/fs/bcachefs/bkey_methods.c b/fs/bcachefs/bkey_methods.c
index db336a43fc083a..a275a9e8e341aa 100644
--- a/fs/bcachefs/bkey_methods.c
+++ b/fs/bcachefs/bkey_methods.c
@@ -171,8 +171,8 @@ int __bch2_bkey_invalid(struct bch_fs *c, struct bkey_s_c k,
 	if (type >= BKEY_TYPE_NR)
 		return 0;
 
-	bkey_fsck_err_on((type == BKEY_TYPE_btree ||
-			  (flags & BKEY_INVALID_COMMIT)) &&
+	bkey_fsck_err_on(k.k->type < KEY_TYPE_MAX &&
+			 (type == BKEY_TYPE_btree || (flags & BKEY_INVALID_COMMIT)) &&
 			 !(bch2_key_types_allowed[type] & BIT_ULL(k.k->type)), c, err,
 			 bkey_invalid_type_for_btree,
 			 "invalid key type for btree %s (%s)",
diff --git a/fs/bcachefs/btree_key_cache.c b/fs/bcachefs/btree_key_cache.c
index e8c1c530cd95f5..7dafa1accec220 100644
--- a/fs/bcachefs/btree_key_cache.c
+++ b/fs/bcachefs/btree_key_cache.c
@@ -956,13 +956,15 @@ void bch2_fs_btree_key_cache_exit(struct btree_key_cache *bc)
 	}
 
 #ifdef __KERNEL__
-	for_each_possible_cpu(cpu) {
-		struct btree_key_cache_freelist *f =
-			per_cpu_ptr(bc->pcpu_freed, cpu);
-
-		for (i = 0; i < f->nr; i++) {
-			ck = f->objs[i];
-			list_add(&ck->list, &items);
+	if (bc->pcpu_freed) {
+		for_each_possible_cpu(cpu) {
+			struct btree_key_cache_freelist *f =
+				per_cpu_ptr(bc->pcpu_freed, cpu);
+
+			for (i = 0; i < f->nr; i++) {
+				ck = f->objs[i];
+				list_add(&ck->list, &items);
+			}
 		}
 	}
 #endif
diff --git a/fs/bcachefs/checksum.c b/fs/bcachefs/checksum.c
index 7ed779b411f61e..088fd2e7bdf126 100644
--- a/fs/bcachefs/checksum.c
+++ b/fs/bcachefs/checksum.c
@@ -102,6 +102,7 @@ static inline int do_encrypt_sg(struct crypto_sync_skcipher *tfm,
 	int ret;
 
 	skcipher_request_set_sync_tfm(req, tfm);
+	skcipher_request_set_callback(req, 0, NULL, NULL);
 	skcipher_request_set_crypt(req, sg, sg, len, nonce.d);
 
 	ret = crypto_skcipher_encrypt(req);
diff --git a/fs/bcachefs/errcode.h b/fs/bcachefs/errcode.h
index 01a79fa3eacb21..dbe35b80bc0b89 100644
--- a/fs/bcachefs/errcode.h
+++ b/fs/bcachefs/errcode.h
@@ -175,6 +175,7 @@
 	x(EINVAL,			block_size_too_small)			\
 	x(EINVAL,			bucket_size_too_small)			\
 	x(EINVAL,			device_size_too_small)			\
+	x(EINVAL,			device_size_too_big)			\
 	x(EINVAL,			device_not_a_member_of_filesystem)	\
 	x(EINVAL,			device_has_been_removed)		\
 	x(EINVAL,			device_splitbrain)			\
diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c
index fce690007edfce..6f114803c6f239 100644
--- a/fs/bcachefs/fs.c
+++ b/fs/bcachefs/fs.c
@@ -964,7 +964,6 @@ static int bch2_fiemap(struct inode *vinode, struct fiemap_extent_info *info,
 	struct btree_iter iter;
 	struct bkey_s_c k;
 	struct bkey_buf cur, prev;
-	struct bpos end = POS(ei->v.i_ino, (start + len) >> 9);
 	unsigned offset_into_extent, sectors;
 	bool have_extent = false;
 	u32 snapshot;
@@ -974,6 +973,7 @@ static int bch2_fiemap(struct inode *vinode, struct fiemap_extent_info *info,
 	if (ret)
 		return ret;
 
+	struct bpos end = POS(ei->v.i_ino, (start + len) >> 9);
 	if (start + len < start)
 		return -EINVAL;
 
diff --git a/fs/bcachefs/io_write.c b/fs/bcachefs/io_write.c
index f137252bccc575..40d7df7607dfd1 100644
--- a/fs/bcachefs/io_write.c
+++ b/fs/bcachefs/io_write.c
@@ -199,9 +199,6 @@ static inline int bch2_extent_update_i_size_sectors(struct btree_trans *trans,
 						    u64 new_i_size,
 						    s64 i_sectors_delta)
 {
-	struct btree_iter iter;
-	struct bkey_i *k;
-	struct bkey_i_inode_v3 *inode;
 	/*
 	 * Crazy performance optimization:
 	 * Every extent update needs to also update the inode: the inode trigger
@@ -214,25 +211,36 @@ static inline int bch2_extent_update_i_size_sectors(struct btree_trans *trans,
 	 * lost, but that's fine.
 	 */
 	unsigned inode_update_flags = BTREE_UPDATE_NOJOURNAL;
-	int ret;
 
-	k = bch2_bkey_get_mut_noupdate(trans, &iter, BTREE_ID_inodes,
+	struct btree_iter iter;
+	struct bkey_s_c k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_inodes,
 			      SPOS(0,
 				   extent_iter->pos.inode,
 				   extent_iter->snapshot),
 			      BTREE_ITER_CACHED);
-	ret = PTR_ERR_OR_ZERO(k);
+	int ret = bkey_err(k);
 	if (unlikely(ret))
 		return ret;
 
-	if (unlikely(k->k.type != KEY_TYPE_inode_v3)) {
-		k = bch2_inode_to_v3(trans, k);
-		ret = PTR_ERR_OR_ZERO(k);
+	/*
+	 * varint_decode_fast(), in the inode .invalid method, reads up to 7
+	 * bytes past the end of the buffer:
+	 */
+	struct bkey_i *k_mut = bch2_trans_kmalloc_nomemzero(trans, bkey_bytes(k.k) + 8);
+	ret = PTR_ERR_OR_ZERO(k_mut);
+	if (unlikely(ret))
+		goto err;
+
+	bkey_reassemble(k_mut, k);
+
+	if (unlikely(k_mut->k.type != KEY_TYPE_inode_v3)) {
+		k_mut = bch2_inode_to_v3(trans, k_mut);
+		ret = PTR_ERR_OR_ZERO(k_mut);
 		if (unlikely(ret))
 			goto err;
 	}
 
-	inode = bkey_i_to_inode_v3(k);
+	struct bkey_i_inode_v3 *inode = bkey_i_to_inode_v3(k_mut);
 
 	if (!(le64_to_cpu(inode->v.bi_flags) & BCH_INODE_i_size_dirty) &&
 	    new_i_size > le64_to_cpu(inode->v.bi_size)) {
@@ -1505,6 +1513,8 @@ static void bch2_write_data_inline(struct bch_write_op *op, unsigned data_len)
 	unsigned sectors;
 	int ret;
 
+	memset(&op->failed, 0, sizeof(op->failed));
+
 	op->flags |= BCH_WRITE_WROTE_DATA_INLINE;
 	op->flags |= BCH_WRITE_DONE;
 
diff --git a/fs/bcachefs/journal.c b/fs/bcachefs/journal.c
index 9c9a25dbd6137a..a8b08e76d0d01e 100644
--- a/fs/bcachefs/journal.c
+++ b/fs/bcachefs/journal.c
@@ -706,6 +706,12 @@ recheck_need_open:
 
 		spin_unlock(&j->lock);
 
+		/*
+		 * We're called from bch2_journal_flush_seq() -> wait_event();
+		 * but this might block. We won't usually block, so we won't
+		 * livelock:
+		 */
+		sched_annotate_sleep();
 		ret = bch2_journal_res_get(j, &res, jset_u64s(0), 0);
 		if (ret)
 			return ret;
@@ -870,6 +876,8 @@ static struct journal_buf *__bch2_next_write_buffer_flush_journal_buf(struct jou
 {
 	struct journal_buf *ret = NULL;
 
+	/* We're inside wait_event(), but using mutex_lock(: */
+	sched_annotate_sleep();
 	mutex_lock(&j->buf_lock);
 	spin_lock(&j->lock);
 	max_seq = min(max_seq, journal_cur_seq(j));
diff --git a/fs/bcachefs/move.c b/fs/bcachefs/move.c
index bf68ea49447b95..4d94b7742dbbae 100644
--- a/fs/bcachefs/move.c
+++ b/fs/bcachefs/move.c
@@ -968,24 +968,30 @@ static bool migrate_btree_pred(struct bch_fs *c, void *arg,
 	return migrate_pred(c, arg, bkey_i_to_s_c(&b->key), io_opts, data_opts);
 }
 
+/*
+ * Ancient versions of bcachefs produced packed formats which could represent
+ * keys that the in memory format cannot represent; this checks for those
+ * formats so we can get rid of them.
+ */
 static bool bformat_needs_redo(struct bkey_format *f)
 {
-	unsigned i;
-
-	for (i = 0; i < f->nr_fields; i++) {
+	for (unsigned i = 0; i < f->nr_fields; i++) {
+		unsigned f_bits = f->bits_per_field[i];
 		unsigned unpacked_bits = bch2_bkey_format_current.bits_per_field[i];
 		u64 unpacked_mask = ~((~0ULL << 1) << (unpacked_bits - 1));
 		u64 field_offset = le64_to_cpu(f->field_offset[i]);
 
-		if (f->bits_per_field[i] > unpacked_bits)
+		if (f_bits > unpacked_bits)
 			return true;
 
-		if ((f->bits_per_field[i] == unpacked_bits) && field_offset)
+		if ((f_bits == unpacked_bits) && field_offset)
 			return true;
 
-		if (((field_offset + ((1ULL << f->bits_per_field[i]) - 1)) &
-		     unpacked_mask) <
-		    field_offset)
+		u64 f_mask = f_bits
+			? ~((~0ULL << (f_bits - 1)) << 1)
+			: 0;
+
+		if (((field_offset + f_mask) & unpacked_mask) < field_offset)
 			return true;
 	}
 
diff --git a/fs/bcachefs/quota.c b/fs/bcachefs/quota.c
index e68b34eab90a91..556da073810695 100644
--- a/fs/bcachefs/quota.c
+++ b/fs/bcachefs/quota.c
@@ -560,13 +560,11 @@ static int bch2_fs_quota_read_inode(struct btree_trans *trans,
 	struct bch_fs *c = trans->c;
 	struct bch_inode_unpacked u;
 	struct bch_snapshot_tree s_t;
-	int ret;
+	u32 tree = bch2_snapshot_tree(c, k.k->p.snapshot);
 
-	ret = bch2_snapshot_tree_lookup(trans,
-			bch2_snapshot_tree(c, k.k->p.snapshot), &s_t);
+	int ret = bch2_snapshot_tree_lookup(trans, tree, &s_t);
 	bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
-			"%s: snapshot tree %u not found", __func__,
-			snapshot_t(c, k.k->p.snapshot)->tree);
+			"%s: snapshot tree %u not found", __func__, tree);
 	if (ret)
 		return ret;
 
diff --git a/fs/bcachefs/recovery.c b/fs/bcachefs/recovery.c
index be5b4761932700..8091d0686029f4 100644
--- a/fs/bcachefs/recovery.c
+++ b/fs/bcachefs/recovery.c
@@ -902,7 +902,8 @@ out:
 		bch2_journal_keys_put_initial(c);
 		bch2_find_btree_nodes_exit(&c->found_btree_nodes);
 	}
-	kfree(clean);
+	if (!IS_ERR(clean))
+		kfree(clean);
 
 	if (!ret &&
 	    test_bit(BCH_FS_need_delete_dead_snapshots, &c->flags) &&
diff --git a/fs/bcachefs/sb-clean.c b/fs/bcachefs/sb-clean.c
index 35ca3f138de6fa..194e55b11137b9 100644
--- a/fs/bcachefs/sb-clean.c
+++ b/fs/bcachefs/sb-clean.c
@@ -278,6 +278,17 @@ static int bch2_sb_clean_validate(struct bch_sb *sb,
 		return -BCH_ERR_invalid_sb_clean;
 	}
 
+	for (struct jset_entry *entry = clean->start;
+	     entry != vstruct_end(&clean->field);
+	     entry = vstruct_next(entry)) {
+		if ((void *) vstruct_next(entry) > vstruct_end(&clean->field)) {
+			prt_str(err, "entry type ");
+			bch2_prt_jset_entry_type(err, le16_to_cpu(entry->type));
+			prt_str(err, " overruns end of section");
+			return -BCH_ERR_invalid_sb_clean;
+		}
+	}
+
 	return 0;
 }
 
@@ -295,6 +306,9 @@ static void bch2_sb_clean_to_text(struct printbuf *out, struct bch_sb *sb,
 	for (entry = clean->start;
 	     entry != vstruct_end(&clean->field);
 	     entry = vstruct_next(entry)) {
+		if ((void *) vstruct_next(entry) > vstruct_end(&clean->field))
+			break;
+
 		if (entry->type == BCH_JSET_ENTRY_btree_keys &&
 		    !entry->u64s)
 			continue;
diff --git a/fs/bcachefs/sb-members.c b/fs/bcachefs/sb-members.c
index 5b8e621ac5eb57..44b3f0cb7b4974 100644
--- a/fs/bcachefs/sb-members.c
+++ b/fs/bcachefs/sb-members.c
@@ -124,9 +124,9 @@ static int validate_member(struct printbuf *err,
 			   struct bch_sb *sb,
 			   int i)
 {
-	if (le64_to_cpu(m.nbuckets) > LONG_MAX) {
-		prt_printf(err, "device %u: too many buckets (got %llu, max %lu)",
-			   i, le64_to_cpu(m.nbuckets), LONG_MAX);
+	if (le64_to_cpu(m.nbuckets) > BCH_MEMBER_NBUCKETS_MAX) {
+		prt_printf(err, "device %u: too many buckets (got %llu, max %u)",
+			   i, le64_to_cpu(m.nbuckets), BCH_MEMBER_NBUCKETS_MAX);
 		return -BCH_ERR_invalid_sb_members;
 	}
 
diff --git a/fs/bcachefs/sb-members.h b/fs/bcachefs/sb-members.h
index 5efa64eca5f85a..5bf27d30ca2969 100644
--- a/fs/bcachefs/sb-members.h
+++ b/fs/bcachefs/sb-members.h
@@ -107,10 +107,10 @@ static inline struct bch_dev *__bch2_next_dev(struct bch_fs *c, struct bch_dev *
 
 static inline struct bch_dev *bch2_get_next_dev(struct bch_fs *c, struct bch_dev *ca)
 {
+	rcu_read_lock();
 	if (ca)
 		percpu_ref_put(&ca->ref);
 
-	rcu_read_lock();
 	if ((ca = __bch2_next_dev(c, ca, NULL)))
 		percpu_ref_get(&ca->ref);
 	rcu_read_unlock();
@@ -132,10 +132,10 @@ static inline struct bch_dev *bch2_get_next_online_dev(struct bch_fs *c,
 						       struct bch_dev *ca,
 						       unsigned state_mask)
 {
+	rcu_read_lock();
 	if (ca)
 		percpu_ref_put(&ca->io_ref);
 
-	rcu_read_lock();
 	while ((ca = __bch2_next_dev(c, ca, NULL)) &&
 	       (!((1 << ca->mi.state) & state_mask) ||
 		!percpu_ref_tryget(&ca->io_ref)))
diff --git a/fs/bcachefs/super-io.c b/fs/bcachefs/super-io.c
index 08ea3dbbbe97ce..bfdb15e7d778e2 100644
--- a/fs/bcachefs/super-io.c
+++ b/fs/bcachefs/super-io.c
@@ -232,7 +232,7 @@ struct bch_sb_field *bch2_sb_field_resize_id(struct bch_sb_handle *sb,
 			struct bch_sb_handle *dev_sb = &ca->disk_sb;
 
 			if (bch2_sb_realloc(dev_sb, le32_to_cpu(dev_sb->sb->u64s) + d)) {
-				percpu_ref_put(&ca->ref);
+				percpu_ref_put(&ca->io_ref);
 				return NULL;
 			}
 		}
@@ -649,7 +649,7 @@ reread:
 
 	bytes = vstruct_bytes(sb->sb);
 
-	if (bytes > 512 << sb->sb->layout.sb_max_size_bits) {
+	if (bytes > 512ULL << min(BCH_SB_LAYOUT_SIZE_BITS_MAX, sb->sb->layout.sb_max_size_bits)) {
 		prt_printf(err, "Invalid superblock: too big (got %zu bytes, layout max %lu)",
 		       bytes, 512UL << sb->sb->layout.sb_max_size_bits);
 		return -BCH_ERR_invalid_sb_too_big;
@@ -923,6 +923,7 @@ int bch2_write_super(struct bch_fs *c)
 	struct bch_devs_mask sb_written;
 	bool wrote, can_mount_without_written, can_mount_with_written;
 	unsigned degraded_flags = BCH_FORCE_IF_DEGRADED;
+	DARRAY(struct bch_dev *) online_devices = {};
 	int ret = 0;
 
 	trace_and_count(c, write_super, c, _RET_IP_);
@@ -935,6 +936,15 @@ int bch2_write_super(struct bch_fs *c)
 	closure_init_stack(cl);
 	memset(&sb_written, 0, sizeof(sb_written));
 
+	for_each_online_member(c, ca) {
+		ret = darray_push(&online_devices, ca);
+		if (bch2_fs_fatal_err_on(ret, c, "%s: error allocating online devices", __func__)) {
+			percpu_ref_put(&ca->io_ref);
+			goto out;
+		}
+		percpu_ref_get(&ca->io_ref);
+	}
+
 	/* Make sure we're using the new magic numbers: */
 	c->disk_sb.sb->magic = BCHFS_MAGIC;
 	c->disk_sb.sb->layout.magic = BCHFS_MAGIC;
@@ -942,8 +952,8 @@ int bch2_write_super(struct bch_fs *c)
 	le64_add_cpu(&c->disk_sb.sb->seq, 1);
 
 	struct bch_sb_field_members_v2 *mi = bch2_sb_field_get(c->disk_sb.sb, members_v2);
-	for_each_online_member(c, ca)
-		__bch2_members_v2_get_mut(mi, ca->dev_idx)->seq = c->disk_sb.sb->seq;
+	darray_for_each(online_devices, ca)
+		__bch2_members_v2_get_mut(mi, (*ca)->dev_idx)->seq = c->disk_sb.sb->seq;
 	c->disk_sb.sb->write_time = cpu_to_le64(ktime_get_real_seconds());
 
 	if (test_bit(BCH_FS_error, &c->flags))
@@ -959,16 +969,15 @@ int bch2_write_super(struct bch_fs *c)
 	bch2_sb_errors_from_cpu(c);
 	bch2_sb_downgrade_update(c);
 
-	for_each_online_member(c, ca)
-		bch2_sb_from_fs(c, ca);
+	darray_for_each(online_devices, ca)
+		bch2_sb_from_fs(c, (*ca));
 
-	for_each_online_member(c, ca) {
+	darray_for_each(online_devices, ca) {
 		printbuf_reset(&err);
 
-		ret = bch2_sb_validate(&ca->disk_sb, &err, WRITE);
+		ret = bch2_sb_validate(&(*ca)->disk_sb, &err, WRITE);
 		if (ret) {
 			bch2_fs_inconsistent(c, "sb invalid before write: %s", err.buf);
-			percpu_ref_put(&ca->io_ref);
 			goto out;
 		}
 	}
@@ -995,16 +1004,18 @@ int bch2_write_super(struct bch_fs *c)
 		return -BCH_ERR_sb_not_downgraded;
 	}
 
-	for_each_online_member(c, ca) {
-		__set_bit(ca->dev_idx, sb_written.d);
-		ca->sb_write_error = 0;
+	darray_for_each(online_devices, ca) {
+		__set_bit((*ca)->dev_idx, sb_written.d);
+		(*ca)->sb_write_error = 0;
 	}
 
-	for_each_online_member(c, ca)
-		read_back_super(c, ca);
+	darray_for_each(online_devices, ca)
+		read_back_super(c, *ca);
 	closure_sync(cl);
 
-	for_each_online_member(c, ca) {
+	darray_for_each(online_devices, cap) {
+		struct bch_dev *ca = *cap;
+
 		if (ca->sb_write_error)
 			continue;
 
@@ -1031,17 +1042,20 @@ int bch2_write_super(struct bch_fs *c)
 
 	do {
 		wrote = false;
-		for_each_online_member(c, ca)
+		darray_for_each(online_devices, cap) {
+			struct bch_dev *ca = *cap;
 			if (!ca->sb_write_error &&
 			    sb < ca->disk_sb.sb->layout.nr_superblocks) {
 				write_one_super(c, ca, sb);
 				wrote = true;
 			}
+		}
 		closure_sync(cl);
 		sb++;
 	} while (wrote);
 
-	for_each_online_member(c, ca) {
+	darray_for_each(online_devices, cap) {
+		struct bch_dev *ca = *cap;
 		if (ca->sb_write_error)
 			__clear_bit(ca->dev_idx, sb_written.d);
 		else
@@ -1077,6 +1091,9 @@ int bch2_write_super(struct bch_fs *c)
 out:
 	/* Make new options visible after they're persistent: */
 	bch2_sb_update(c);
+	darray_for_each(online_devices, ca)
+		percpu_ref_put(&(*ca)->io_ref);
+	darray_exit(&online_devices);
 	printbuf_exit(&err);
 	return ret;
 }
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 88e214c609bb2b..dddf57ec4511f3 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -1959,6 +1959,13 @@ int bch2_dev_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
 		goto err;
 	}
 
+	if (nbuckets > BCH_MEMBER_NBUCKETS_MAX) {
+		bch_err(ca, "New device size too big (%llu greater than max %u)",
+			nbuckets, BCH_MEMBER_NBUCKETS_MAX);
+		ret = -BCH_ERR_device_size_too_big;
+		goto err;
+	}
+
 	if (bch2_dev_is_online(ca) &&
 	    get_capacity(ca->disk_sb.bdev->bd_disk) <
 	    ca->mi.bucket_size * nbuckets) {
@@ -2004,13 +2011,9 @@ err:
 /* return with ref on ca->ref: */
 struct bch_dev *bch2_dev_lookup(struct bch_fs *c, const char *name)
 {
-	rcu_read_lock();
-	for_each_member_device_rcu(c, ca, NULL)
-		if (!strcmp(name, ca->name)) {
-			rcu_read_unlock();
+	for_each_member_device(c, ca)
+		if (!strcmp(name, ca->name))
 			return ca;
-		}
-	rcu_read_unlock();
 	return ERR_PTR(-BCH_ERR_ENOENT_dev_not_found);
 }